LibJS: Implement the Temporal.PlainMonthDay constructor

And the simple Temporal.PlainMonthDay.prototype getters, so that the
constructed Temporal.PlainMonthDay may actually be validated.

Libraries/LibJS/Runtime/Temporal/PlainTime.cpp

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2021, Idan Horowitz <idan.horowitz@serenityos.org>
+ * Copyright (c) 2021-2023, Linus Groh <linusg@serenityos.org>
+ * Copyright (c) 2024, Tim Flynn <trflynn89@ladybird.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/Assertions.h>
+#include <LibJS/Runtime/Temporal/PlainTime.h>
+
+namespace JS::Temporal {
+
+// 4.5.2 CreateTimeRecord ( hour, minute, second, millisecond, microsecond, nanosecond [ , deltaDays ] ), https://tc39.es/proposal-temporal/#sec-temporal-createtimerecord
+Time create_time_record(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond, double delta_days)
+{
+    // 1. If deltaDays is not present, set deltaDays to 0.
+    // 2. Assert: IsValidTime(hour, minute, second, millisecond, microsecond, nanosecond).
+    VERIFY(is_valid_time(hour, minute, second, millisecond, microsecond, nanosecond));
+
+    // 3. Return Time Record { [[Days]]: deltaDays, [[Hour]]: hour, [[Minute]]: minute, [[Second]]: second, [[Millisecond]]: millisecond, [[Microsecond]]: microsecond, [[Nanosecond]]: nanosecond  }.
+    return {
+        .days = delta_days,
+        .hour = static_cast<u8>(hour),
+        .minute = static_cast<u8>(minute),
+        .second = static_cast<u8>(second),
+        .millisecond = static_cast<u16>(millisecond),
+        .microsecond = static_cast<u16>(microsecond),
+        .nanosecond = static_cast<u16>(nanosecond),
+    };
+}
+
+// 4.5.4 NoonTimeRecord ( ), https://tc39.es/proposal-temporal/#sec-temporal-noontimerecord
+Time noon_time_record()
+{
+    // 1. Return Time Record { [[Days]]: 0, [[Hour]]: 12, [[Minute]]: 0, [[Second]]: 0, [[Millisecond]]: 0, [[Microsecond]]: 0, [[Nanosecond]]: 0  }.
+    return { .days = 0, .hour = 12, .minute = 0, .second = 0, .millisecond = 0, .microsecond = 0, .nanosecond = 0 };
+}
+
+// 4.5.9 IsValidTime ( hour, minute, second, millisecond, microsecond, nanosecond ), https://tc39.es/proposal-temporal/#sec-temporal-isvalidtime
+bool is_valid_time(double hour, double minute, double second, double millisecond, double microsecond, double nanosecond)
+{
+    // 1. If hour < 0 or hour > 23, then
+    if (hour < 0 || hour > 23) {
+        // a. Return false.
+        return false;
+    }
+
+    // 2. If minute < 0 or minute > 59, then
+    if (minute < 0 || minute > 59) {
+        // a. Return false.
+        return false;
+    }
+
+    // 3. If second < 0 or second > 59, then
+    if (second < 0 || second > 59) {
+        // a. Return false.
+        return false;
+    }
+
+    // 4. If millisecond < 0 or millisecond > 999, then
+    if (millisecond < 0 || millisecond > 999) {
+        // a. Return false.
+        return false;
+    }
+
+    // 5. If microsecond < 0 or microsecond > 999, then
+    if (microsecond < 0 || microsecond > 999) {
+        // a. Return false.
+        return false;
+    }
+
+    // 6. If nanosecond < 0 or nanosecond > 999, then
+    if (nanosecond < 0 || nanosecond > 999) {
+        // a. Return false.
+        return false;
+    }
+
+    // 7. Return true.
+    return true;
+}
+
+}